Topical skin care compositions containing actives that provide benefits to skin are well known. It also known that the skin health and appearance benefits provided by a cosmetic skin care active may be improved when the active can penetrate deeper into the skin. For example, peptides (e.g., di-, tri-, tetra- and pentapeptides) and their derivatives, which are known for use in regulating a variety of skin conditions, typically need to penetrate skin to provide the desired benefit. In one particular example, the peptide derivative palmitoyl-lysine-threonine-threonine-lysine-serine, also known as Pal-KTTKS (SEQ ID NO: 1), is used in skin care compositions to improve the signs of skin aging. It is believed, without being limited by theory, that Pal-KTTKS (SEQ ID NO: 1) stimulates collagen production in the dermal fibroblasts, which are the skin cells primarily responsible for collagen production, resulting in a reduction of the appearance of fine, lines and wrinkles. However, to reach the dermal fibroblasts, the Pal-KTTKS (SEQ ID NO: 1) must penetrate through the epidermal layers of the skin. Thus, it would be desirable to find a suitable way to improve the skin penetration of cosmetic skin care actives such as Pal-KTTKS (SEQ ID NO: 1).
However, effective delivery of skin care actives, such as Pal-KTTKS (SEQ ID NO: 1), into skin is an ongoing challenge. It is not uncommon for skin care actives to be introduced to skin via topical application of, for example, creams, lotions and essences. However, the actual and perceived benefits of skin care actives such as Pal-KTTKS (SEQ ID NO: 1) are largely dependent on the amount of skin care active that penetrates the top layer of skin and the depth to which it penetrates. There are various factors that limit the amount of active agent that can penetrate skin, and at present there is little control over the positioning and residency of the active agents following penetration into skin.
The amount of active agent provided in a skin care composition can be increased in various ways, for example, by increasing the amount of active agent in the skin care composition. However, this often leads to compositions that do not have a good sensory feel, increased formulation challenges, stability issues and increased manufacturing costs.
One approach to improving the efficacy of a skin care active is to use chemical penetration enhancers to facilitate changes in skin permeability, allowing enhanced penetration of the skin care active. However, the use of chemical penetration enhancers can be problematic due to unknown interaction with the active agent and the potential for adverse side effects such as irritation of skin and mucosal surfaces.
Mechanical approaches to increasing skin penetration of actives have also been explored. For example, one such approach known as iontophoresis utilizes an electrical energy gradient to accelerate a charged active agent(s) across the skin (or other barrier). An example of a device that uses iontophoresis is described in U.S. Pat. No. 7,137,965. However, iontophoresis is only suitable for specific active agents with certain ionic structures and can be injurious to certain dermal barriers due to exchange ion degradation. Additionally, iontophoresis requires the use of intimate electrical contact and adhesive electrodes, which are not suitable for all target surfaces or barriers.
Other techniques for creating mobility and/or direction in the movement of active agent(s) include magnetokinetics and magnetophoresis. However, these techniques have been difficult to implement due to poor performance, high hardware and energy requirements, and cost. An example of a device that utilizes magnetophoresis is described in US 2009/0093669. While these methods claim to increase the amount of penetration of skin care actives into skin, they still do not provide enhanced penetration in a controlled manner—both in terms of amount of penetration and depth of penetration.
In another example of a device design to effectively deliver skin care actives, WO 2011/156869 discloses a method of delivering a skin care agent through a dermal barrier using one or more displaced dipolar magnetic elements. However, this method still does not provide a targeted approach that takes account of the unique properties and targeted benefit areas in skin of different skin care actives.
Accordingly, there is a need to provide a cosmetic product that can provide improved penetration of specific cosmetic actives into skin in a controlled manner.